This invention relates to a method to dealcoholize partially or totally wine and/or cider by using the so-called technique of reverse osmosis.
It relates also to apparatus to implement this method.
Different processes have been used to attempt to remove the alcohol from various alcoholic beverages such a wine, beer, cider, etc. Among these processes, the oldest is evaporation which leads to a product which having undergone a heat treatment, is spoiled, having a taste of "cooked" (grapes, etc.) and whose aromas were modified during the operation. In addition, these methods require a great amount of energy, so that the cost of the final product is influenced to a large extent by the consumption of energy of the installations.
Reverse osmosis to partially dealcoholize wines, consisting of passing the untreated wine through membranes to separate from this wine a permeate constituted by a mixture of water and alcohol, and of replacing the exact volume of this permeate with an equivalent volume of water, demineralized or not, has already been the subject of numerous tests described in several publications that are analyzed below.
European patent application No. EP-A-0162240 describes a process and an installation to dealcoholize alcoholic beverages by reverse osmosis. The permeate removed from the osmotic module is vacuum distilled to be dealcoholized, and then it is added to the retentate in order to give it back aromas originating in the original beverage and to reduce the injection of water. If desired, to eliminate completely any addition of water, the removed alcohol may be replaced with vacuum distilled wine added to the permeate coming out of the osmotic module.
The technique of vacuum distillation used to isolate the aromas of the permeate causes a degradation of these aromas, so that the residual substances added to the retentate never make it possible to give back to this retentate the bouquet of the original beverage.
German patent application DE-A 23 39 206 describes another method to dealcoholize wine or other alcoholic beverages by a technique using the principle of reverse osmosis. The mixture of water and alcohol removed is replaced with water, and the process provides for the addition, after the treatment, of weakly fermented fruit juices to restore a semblance of initial taste.
German patent application DE-A 23 23 094 describes also a process to dealcoholize beer by reverse osmosis. According to a principle analogous to the one described in the above-mentioned European patent application, the alcohol is removed from the permeate and this permeate is added either to the retentate, or to the original beverage prior to its introduction in the osmotic module.
The analysis of these different publications shows very clearly that one of the main concerns of all those who have tried to dealcoholize alcoholic beverages by applying a method based on reverse osmosis were confronted with the problem of deterioration of the taste and the aroma of the beverage obtained after the treatment. However, none of the approaches used in trying to solve this problem led to an acceptable result. The use of heat treatments to remove the alcohol from the permeate generates inevitably a deterioration of the bouquet and of the aroma. The addition of a controlled amount of original liquid can never restore the original taste and aroma since the reintroduced substances are too strongly diluted to transmit their characteristics to the whole volume treated, especially if in the final product a percentage of alcohol of less than 0.7% is to be preserved.
As a result, dealcoholized beverages and more specifically dealcoholized wines obtained with the methods known to this day no longer possess the qualities of taste and aroma that make them a product appreciated by the consumer.